This invention relates to cyclic dodecapeptide analogs of somatostatin and intermediates employed in their synthesis by a combination of the solid phase and classical method of peptide synthesis.
Somatostatin (also known as somatotropin release inhibiting factor or SRIF) is the tetradecapeptide ##STR2## This tetradecapeptide has been identified by isolation from extracts of ovine hypothalamic tissues and found to inhibit the secretion of the hormone somatotropin which is commonly referred to as the growth hormone (GH); See Brazeau et al., Science, 179 pp 77-79 (January 1973). The linear form of this tetradecapeptide, H--Ala--Gly--Cys--Lys--Asn--Phe--Phe--Trp--Lys--Thr--Phe--Thr--Ser--Cys--O H, has also been reported by Brazeau et al., supra, to have been synthesized by solid phase methodology and found to have the same biological activity as the somatostatin obtained from a natural source.